Silent secondary clock



April 24, 1928.

T. S. CASNER SILENT SECONDARY CLOCK Filed May 29, 1926 Patented Apr. 24, 1928.

man STATES AT j T ELECTRIC CLOCK CORPORATION, OF WARE.

' THAIDJDEUS STEPHENS CASNER, OF PLAINFIELD, NEW JERSEY, ASSIGNOR TO RADIO NEW YORK, N. Y., A CORPORATION OF DELA SILENT SECONDARY CLOCK.

Application filed May 29,

This invention relates to intermittently operating electrical devices and particularly to electro-magnetically operated clocks.

The principal object of this invention is to provide an improved drive mechanism for intermittently operating devices such as electrical secondary clocks, which are in circuit with a control device for instance a master clock, which makes and breaks a circuit through a source of electrical energy.

An objectionable feature of devices of this character heretofore created or suggested is that a mechanical, usually metallic, sound is made whenever the electrical driving mechanism is operated. This sound is in some cases caused by an armature oscillating between fixed stops, in other cases by the movement of pawls over ratchets, and by various other operating parts. It is ObVlOllS that where quiet is desired, as for instance n hotel rooms, in schools, in theatres, and in rivate homes, these noises, however faint, Because of their metallic character and ceaseless regularity are irritating to persons situated near the instrument.

The present invention therefore has for a further object the provision of electromagnetic drive mechanism which shall be noiseless in its operation, and which shall have no parts the operation of which may result in audible sounds.

A further object of the invention is the provision of an apparatus of this class having few parts and these of a simple character, WhlCll is readily accessible for cleaning and oiling, and which is of small size, rendering it convenient for use with wall clocks, desk clocks, punch clocks, automatic temperature recording mechanisms, se1smographs, and many other devices. I

The invention will be described as applied to'secondary electric clocks though it will be evident that it is adapted to be used with various other devices. One form of the invention is described herein and illustrated the accompanying drawings, in which:

Fig. 1 is a front elevation of a secondary clock embodying this invention, the gearing to the clock hand shafts other than the minute shaft being omitted for the sake of clearness;

Fig. is side elevation of the device shown in Figure 1; and a 1926. Serial No. 112,542.

Fig. 3 is an enlarged view of a detail shown in Figure 1, parts being shown in a different position.

A pair of electro-magnets M, M are connected together by a fixed yoke A which for convenience is bent downwardly along the sides of the magnets to form bearings for the shafts of the mechanism operated b the magnets, as will be described below. The poles P, P of the magnets are formed with concavities ll, 11 along their sides or at their ends to allow a moving armature 12 to rotate therebetween. This armature is made approximately Z-shaped with the exception of the Wings 13 of the armature, which are given a curved outline to move with a variable clearance between the concavities of the pole pieces. The wings of the armature are made of varying cross sectional area from the tip to the heel, having the greatest area near the heel. This construction provides the proper rotatable pull upon the armature when the magnet is energized. A shaft 14 rotatably supports the armature l2v between the pole pieces, the bent portions 15 of the yoke A having bearings 16 formed therein for this purpose.

Another shaft 18 is also rotatably carried in bearings 19 in the extensions 15. The shaft 18 constitutes the minute shaft of the secondary clock when the mechanism is used for operating a secondary clock. This is provided for by securingthereon a toothed wheel 20 which has sixty teeth so that it makes one revolution every hour when geared to mechanism designed to move it through the distance of one tooth space per minute. The shaft 18 also carries a pinion 21 designed to connect it to the hour hand of the secondary clock through the usual gearing.- The illustration of this gearing is omitted from the drawings for the sake of clearness.

The shaft 14 carries, in addition to the armature 12, a disk 25, rigidly secured thereto. The disk 25 is thus rotatable with the armature and operates the toothed wheel 20 of the minute shaft through two pins 26, 26 secured to one side of the disk on opposite sides of, and in axial alignment with, the shaft. The purpose of having two pins instead of a greater number is to provide a one-way drive for the clock hands.

With this drive arran ement the clock gear train cannot be move 'except by the armature and pins and .hence the hands cannot be accidentally moved to give the clock a Wrong setting. It is 'also to be noted that vthe pins 26 are disposed in a line oblique moving slowly from rest all metallic blows and noises between these arts are avoided.

On the opposite side t e disk carries a second pair of ins 30 spaced approximately 90 from the .rst pair of pins. The pins 30 operate against a spring 35 having its axis generally parallel to a line joining shafts 14 and 18. In its preferred form the spring is of the hair pin type, as illustrated, to provide a balanced pressure on the sides of shaft 14, though it is evident that a single pronged sprin "might be used. The spring 35 is supporte by a screw 36 secured in one of the yoke extensions 15. Preferably also the pins 30 carry grooved rollers 31 to rovide easy movement along the prongs o the sprin In the position of rest the rollers are a igned along the axis of and between the prongs of the spring'as shown in Figure 1. In this position the prongs of the spring bear but lightly on the rollers and no considerable force is required to be exerted on the armature to move the rollers against the spring pressure.

The operation of the mechanism will be apparent. Closure of a switch by a master clock at minute intervals causes the armature to be moved from the position of rest, shown in Figure 1 to the position shown in Figure 3 wherein the bar of the Z-shaped magnet is aligned between the magnet poles. In this movement of the armature, which is greater than 90 the rollers between the springs-are moved from the aligned position to a position just beyond dead center with respect to the springs. Then when the master clock breaks circuit to deenergize magnets, the sprin 35 by pressing on the rollers causes the sha t to complete a movement of 180 from the initial position and thereby move the toothed wheel by pins 26 through a distance of one tooth space. The spring 35 is made just strong enough to cause the rollers to move when the magnet is deener ized but not strong enough to rotate the ro lers and shaft with sufiicient force to causebar-blmv when the rollers contact the opposite prongs of the spring at the end of the movement- Having thus described the invention what is claimed as new and desired to be secured by Letters Patent is:

1. Mechanism for intermittently rotating a shaft or other rotatable element, including, a shaft, a disk mounted on the shaft, two pins carried by the disk on opposite sides of the shaft, a toothed wheel meshing with said pins, two rollers also carried by the disk on opposite sides of the shaft and spaced approximately 90 from the pins, a spring adapted to bear against the rollers and to yieldably hold the shaft in either of two definite normal positions 180 apart, and means for initiating movement of the shaft to rotate the rollers thru an angle greater than 90 from either normal position, the spring then act-ing on the rollers to cause the shaft to complete a movement of 180 from initial normal position to cause said pins to move the toothed wheel through the distance of one tooth space.

2. Mechanism for intermittently rotating a shaft or other rotatable element, including, a shaft, a disk mounted on the shaft, two pins carried by the disk on opposite sides of the shaft, a toothed wheel meshing with said pins, two rollers also carried by the disk on opposite sides of the shaft and spaced approximately 90 from the pins, a spring adapted to bear against the rollers and to yieldably hold the shaft in either of two definite normal positions 180 apart, and means for initiating movement of the shaft to rotatethe rollers thru an angle greater than 90 from either normal position, said means including a Z-shaped armature carried by the shaft between the poles of an electro-magnet havin the axis of the connecting bar thereof 0 lique to the line joining said pins, the spring being operative when the armature is released by the magnet to complete a movement of 180 from the initial normal position to cause said pins to move the toothed wheel through the distance of one tooth space.

3; A ma netic secondary clock, comprising in com ination, an electro-magnet having aligned and spaced poles, a Z-shaped armature supported on a shaft between the poles, a disk carried by the shaft, a pair of pins carried by the disk on opposite sides of and coaxial \with the shaft, the pins being disposed at an obli ue angle to the axis of the connecting bar 0 the armature, a toothed wheel meshing with said pins, a second pair of pins also carried by said disk and disposed at an. angle of approximately 90 rom the first pair of pins, a hair pin spring engaging the second pair of pins to yieldingly hold the shaft in either of two definite normal positions 180 apart, said magnet when energized causing said second pair of pins to rotate thru an angle greater than 90 rom the normal position so that when the armature is released the spring will act on a eeasoe lution, said toothed Wheel being advanced one tooth by said pins for each half revolution of said second shaft.

5. A device as claimed in claim 4 in which said second shaft also carries a pair of spaced rollers thereon, and resilient means normally tending to maintain said rollers and shaft in such position that an axial plane passing thru the pins is tangential to the toothed wheel.

In testimony whereof I hereunto ailix my signature.

THADDEUS STEPHENS CASNER. 

